Case Control Study
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World J Gastroenterol. Jan 14, 2022; 28(2): 230-241
Published online Jan 14, 2022. doi: 10.3748/wjg.v28.i2.230
Obesity is associated with decreased risk of microscopic colitis in women
Robert S Sandler, Temitope O Keku, John T Woosley, Dale P Sandler, Joseph A Galanko, Anne F Peery
Robert S Sandler, Temitope O Keku, Joseph A Galanko, Anne F Peery, Department of Medicine, University of North Carolina, Chapel Hill, NC 27514-7555, United States
John T Woosley, Department of Pathology, University of North Carolina, Chapel Hill, NC 27514, United States
Dale P Sandler, Department of Health and Human Services, National Institute of Environmental Health Sciences, Durham, NC 27709, United States
Author contributions: Sandler RS and Keku TO designed the research and obtained funding; Sandler RS, Keku TO and Woosley JT acquired the data; Sandler RS, Keku TO, Woosley JT, Galanko JA, Sandler DP and Peery AF analyzed and interpreted the data and wrote the paper.
Supported by the National Institutes of Health, No. P30 DK034987 and No. R01 DK105114.
Institutional review board statement: The study was approved by the University of North Carolina Office of Human Research Ethics. All patients gave informed consent.
Conflict-of-interest statement: Disclosures: None of the authors have financial, professional or personal conflicts of interest.
Data sharing statement: Data will not be available to other researchers.
STROBE statement: The authors have read the STROBE Statement - checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Robert S Sandler, MD, MPH, Professor, Department of Medicine, University of North Carolina, No. 130 Mason Farm Road, Chapel Hill, NC 27599-7555, United States. rsandler@med.unc.edu
Received: September 12, 2021
Peer-review started: September 12, 2021
First decision: October 16, 2021
Revised: October 18, 2021
Accepted: December 31, 2021
Article in press: December 31, 2021
Published online: January 14, 2022
Processing time: 120 Days and 13.6 Hours
Abstract
BACKGROUND

Microscopic colitis is a leading cause of diarrhea in the older adults. There is limited information about risk factors. We hypothesized that obesity would be associated with microscopic colitis.

AIM

To examine the association between obesity and microscopic colitis in men and women undergoing colonoscopy.

METHODS

We conducted a case-control study at the University of North Carolina Hospitals. We identified and enrolled men and women referred for elective, outpatient colonoscopy for chronic diarrhea. We excluded patients with a past diagnosis of Crohn’s disease or ulcerative colitis. A research pathologist reviewed biopsies on every patient and classified them as microscopic colitis cases or non-microscopic colitis controls. Patients provided information on body weight, height and exposure to medications via structured interviews or Internet based forms. The analysis included 110 patients with microscopic colitis (cases) and 252 non-microscopic colitis controls. Multivariable analyses were performed using logistic regression to estimate odds ratios and 95% confidence intervals.

RESULTS

Cases were older and more likely than controls to be white race. Study subjects were well educated, but cases were better educated than controls. Cases with microscopic colitis had lower body mass index than controls and reported more weight loss after the onset of diarrhea. Compared to patients who were normal or under-weight, obese (BMI > 30 kg/m2) patients were substantially less likely to have microscopic colitis after adjusting for age and education, adjusted OR (aOR) 0.35, 95% confidence interval (CI) 0.18-0.66). When stratified by sex, the association was limited to obese women, aOR 0.21, 95%CI: 0.10-0.45. Patients with microscopic colitis were more likely to report weight loss after the onset of diarrhea. After stratifying by weight loss, there remained a strong inverse association between obesity and microscopic colitis, aOR 0.33, 95%CI: 0.10 – 1.11 among the patients who did not lose weight. Ever use of birth control pills was associated with lower risk of microscopic colitis after adjusting for age, education and BMI, aOR 0.38, 95%CI: 0.17-0.84.

CONCLUSION

Compared to controls also seen for diarrhea, microscopic colitis cases were less likely to be obese. Mechanisms are unknown but could involve hormonal effects of obesity or the gut microbiome.

Keywords: Colitis; Microscopic/epidemiology; Humans; Diarrhea/epidemiology; Obesity

Core Tip: We conducted a case control study among patients undergoing colonoscopy for diarrhea. The analysis included 110 patients with microscopic colitis and 252 controls. Obesity was associated with a substantially lower risk of microscopic colitis among women that was not explained by weight loss following the onset of diarrhea. Ever use of birth control pills was associated with lower risk of microscopic colitis after adjusting for age, education and BMI. The mechanism could involve hormonal effects of obesity or the gut microbiome.